Many kinds of electronic content are delivered over the Internet, such as articles, catalog pages, electronic books, music, etc. For example, VERSAWARE.COM provides consumers with electronic library capability, wherein the consumer can store data culled from reference books, encyclopedias, almanacs and the like. Many systems require the consumer to purchase the content or at least pay for use of the content. In such cases, downloading of the content is usually secured by an encrypted link.
When a consumer buys a tangible item, for example, a book or souvenir from a store, the consumer can transfer the item to another consumer, such as by selling, lending or renting the item. However, when a consumer purchases or pays for the use of electronic content, many kinds of electronic delivery systems prevent the consumer from transferring the content to another.
The following example is a classic case in point. A university student typically purchases text books at the beginning of a semester, and resells the books, either back to the store or to another student, usually at a lower price. If the student drops out of the course for some reason, is perhaps dissatisfied with the particular book, or has never even read the book, he/she can usually return the book to the store. However, the situation is different in the event that a student downloads an electronic book from the web. First, as mentioned above, the electronic delivery system generally prevents the student from transferring the content to another person. Second, even if the student did not read or use the electronic content, it is not generally possible to return the content to the provider and receive one's money back.
Systems are known in the prior art for protecting against unauthorized distribution of documents that were received by a consumer from an electronic content provider. European Patent EP 999488, assigned to XEROX Corporation, describes a system for creating a self-protected document, and which prevents users from obtaining a useful form of an electronically distributed document during the decryption and rendering processes. The system has a polarization key which is used by a polarizer to transform the document to a version having polarized contents. The polarization key represents a combination of data elements taken from the user system's internal state, such as the date and time of day, elapsed time since the last keystroke, the processor's speed and serial number, and any other information that can be repeatably derived from the user system. Time-derived information may also be included in the polarization key so that interception and seizure of the polarized contents is rendered useless.
Published PCT patent application WO 00/08909, assigned to IBM Corporation, describes a secure digital content distribution system that decrypts a decryption key from an encrypted decrypting key. The decrypted decrypting key is transferred to another system. The secure digital content distribution system is capable of communicating with another system which is capable of receiving data encrypted with the encryption key and the encrypted encryption key. The system enables making digital content available to a wide range of users and businesses while ensuring protection and metering of digital assets. The system includes rights management to allow secure delivery, licensing, authorization, and control of the usage of digital assets. The system provides retailers of electronic content a way to differentiate themselves from each other and the content owners when selling music through electronic distribution.
In the WO 00/08909 system, a clearinghouse is maintained by the system for the management of the electronic content (see pages 52-53 of WO 00/08909, entitled “A. Overview”). Content rights may be transferred by electronic digital content stores, content providers or by authorized end-user devices. However, every transfer of rights, even from one authorized end-user device to another, must always be authorized by and transacted through the clearinghouse. It is not possible for an authorized end-user device to transfer content rights independently of the clearinghouse.